With increasing penetration of wind power generation, the requirements for the connection of Wind Power Plants (WPP) to the electrical grid are defined by new and emerging grid connection codes. I order to full fill these grid codes, more and more often modern wind turbine generators are equipped with some sort of a power electronic converter, designed to convert variable frequency electrical power from the generator to fixed frequency power at a connection point in the grid and to provide services that enables the individual wind turbine generator or a plurality of wind turbine generator help reaching the requirements, this type of converter is also known as a variable frequency drive. The type of power electronic converter most often used has some sort of energy storage in the DC link, connecting the generator side of the converter with the grid side of the converter. A requirement for this type a converter to function properly is that the DC link is charged sufficiently prior to operation.
Charging the DC link is known from the prior art, but it requires an additional pre-charge rectifier. Hence, it would be advantageous, and in particular a more efficient and/or reliable if the additional pre-charge rectifier can be omitted. A disadvantage of using the pre-charge rectifier is that when used it causes large in-rush currents, even if the pre-charge rectifier has a current limit, as there will always be a trade-off between in-rush current and time to charge the capacitors in the DC link.